Dark solitons in dual-core waveguides with dispersive coupling

TL;DR

This paper introduces new types of stable two-component dark solitons in dual-core waveguides with dispersive coupling, expanding understanding of their stability and phase properties in nonlinear optical systems.

Contribution

It presents the discovery of novel dark soliton solutions supported by dispersive coupling in dual-core waveguides, including conditions for their stability and phase configurations.

Findings

Gray solitons are stable with out-of-phase backgrounds.

Black solitons can be stable with strong dispersive coupling.

Out-of-phase background solitons extend to phase mismatch cases.

Abstract

We report on new types of two-component one-dimensional dark solitons (DSs) in a model of a dual-core waveguide with normal group-velocity dispersion and Kerr nonlinearity in both cores, the coupling between which is dispersive too. In the presence of the dispersive coupling, quiescent DSs supported by the zero-frequency background are always gray, being stable with the out-of-phase background, i.e., for opposite signs of the fields in the cores. On the contrary, the background with a nonzero frequency supports quiescent black solitons which may be stable for both out- and in-phase backgrounds, if the dispersive coupling is sufficiently strong. Only DSs supported by the out-of-phase background admit an extension to the case of nonzero phase mismatch between the cores.